1. Field of the Invention
The present invention relates generally to branch pipe lining techniques, and more particularly, to a branch pipe liner bag for lining the inner wall of a branch pipe. The present invention is also directed to a pipe lining method for lining a branch pipe and a main pipe.
2. Description of the Related Art
When a branch pipe of passageways or the like is lined, a branch pipe liner bag 101 having a flange 106 formed on one end thereof, as illustrated in FIG. 12, is used. The flange 106 is kept in close contact with the periphery of a branch pipe opening (a portion of a branch pipe 121 open to a main pipe 120) of a main pipe (sewerage line) 120, and the branch pipe liner bag 101 is everted upwardly into the branch pipe 121 by a fluid pressure, as indicated by broken lines in FIG. 12.
Then, after the branch pipe liner bag 101 is fully everted into the branch pipe 121, the branch pipe liner bag 101 is kept pressed onto the inner wall of the branch pipe 121, and a thermosetting resin impregnated in the branch pipe liner bag 101 is hardened. In this way, the branch pipe 121 is lined with the hardened branch pipe liner bag 101.
Conventionally, the branch pipe liner bag 101 has been manufactured by outwardly folding one end of a tubular resin absorbent material made of unwoven fabric or the like, impregnating a hardenable resin into the folded portion, and hardening the impregnated hardenable resin to integrally form the flange 106 (see, for example, Japanese Patent No. 2,528,430).
However, since the conventional branch pipe liner bag 101 is integrally formed with the flange 106 at one end thereof, its manufacturing must rely on manual works of craftsmen. This form of manufacturing implies problems of inaptitude for stabilized quality and mass production as well as a high manufacturing cost.
In addition, when branch pipe liner bags are to be manufactured for stock, they are manufactured slightly longer than actual lengths thereof so as to support a variety of different lengths of branch pipes. Therefore, during a lining operation, a branch pipe liner bag is cut to the actual length of a branch pipe which is to be lined, so that a portion of a branch pipe liner bag is wasted without serving for lining, causing a problem from an economical point of view.
Incidentally, when the branch pipe 121 has been lined as illustrated in FIG. 12, a main pipe liner bag 133 is everted into the main pipe 120 by a fluid pressure as illustrated in FIG. 13. Then, after the eversion of the main pipe liner bag 133 into the main bag 120 is completed, a hardenable resin impregnated in the main pipe liner bag 133 is hardened to line the main pipe 120. Finally, a portion of the main pipe liner bag 133 blocking the branch pipe opening is cut by a cutter, not shown, to allow the branch pipe 121 to communicate with the main pipe 120, as illustrated in FIG. 14, thus completing a sequence of lining operations for the branch pipe 121 and the main pipe 120.
In the conventional pipe lining method mentioned above, however, since the flange 106 of the branch pipe liner bag 101 is not always joined completely with the main pipe liner bag 133, underground water or the like is likely to introduce into the pipes from the joint of the flange 106 and the main pipe liner bag 133.